Display screen or portion thereof with transitional graphical user interface



FIG. 1 is a front view of a first image for a display screen or portion thereof with transitional graphical user interface showing our new design;

FIG. 2 is a second image thereof;

FIG. 3 is a front view of a first image in a second embodiment for a display screen or portion thereof with transitional graphical user interface showing our new design;

FIG. 4 is a second image thereof;

FIG. 5 is a front view of a first image in a third embodiment for a display screen or portion thereof with transitional graphical user interface showing our new design; and,

FIG. 6 is a second image thereof.

The appearance of the transitional image sequentially transitions between the images shown in FIGS. 1-2, FIGS. 3-4 and FIGS. 5-6, respectively. The process or period in which one image transitions to another image forms no part of the claimed design.

The broken lines around the Figures showing a display screen or portion thereof form no part of the claimed design. The broken lines within the Figures show portions of the graphical user interface that form no part of the claimed design. 

CLAIM The ornamental design for a display screen or portion thereof with transitional graphical user interface, as shown and described. 